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AXPZ20 KNHC 182120
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT APR 18 2015

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2100 UTC.


...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

ITCZ AXIS EXTENDS FROM 04N102W TO 02N113W TO 05N135W. SCATTERED MODERATE ISOLATED STRONG CONVECTION FROM 06N TO 12N BETWEEN 131W AND 137W.


...DISCUSSION...

E OF 120W...A WEAK PRESSURE PATTERN CONTINUES ACROSS THE REGION. RECENT SHIP OBS AND SCATTEROMETER SATELLITE DATA INDICATE MAINLY LIGHT TO GENTLE WINDS. ALTIMETER DATA IS SHOWING WAVE HEIGHTS TO 7 FT W OF THE GALAPAGOS ISLANDS FROM SOUTHERLY SWELL. ELSEWHERE SEAS ARE GENERALLY 4-5 FT. DIVERGENCE ALOFT IS ENHANCING MODEST CONVECTION ALONG A TROUGH EXTENDING FROM 07N95W TO 05N101W. PREVIOUS SCAT DATA SHOWED 15-20 KT SOUTHERLY CROSS-EQUATORIAL FLOW CONVERGING INTO NEARLY CALM WINDS TO PRODUCE SHOWERS AND THUNDERSTORMS WITHIN 120 NM OF A LINE FROM 00N97W TO 00N105W.

W OF 120W...A LARGE AREA OF ACTIVE CONVECTION CONTINUES FROM 05N- 12N W OF 130W...LARGELY DUE TO LOW LEVEL TRADE WIND CONVERGENCE AND DIVERGENT FLOW ALOFT BETWEEN A SHARP UPPER TROUGH NW OF AREA AND A BROAD UPPER RIDGE CENTERED NEAR 10N123W. A SURFACE TROUGH ALONG 137W IS NEARLY STATIONARY. FRESH TRADE WINDS PERSIST N OF THE CONVERGENCE ZONE AND S OF A MODERATELY STRONG SUBTROPICAL RIDGE. LONG PERIOD NW SWELL CONTINUES TO PROPAGATE INTO THE REGION. ALTIMETER DATA SHOW 8-9 FT SEAS FROM 10N-20N. FOLLOWING ECWAVE GUIDANCE...WHICH IS MORE INDICATIVE OF ENSEMBLE MEANS INDICATING 8 FT SWELL WILL PERSIST INTO EARLY MON...WHILE THE MWW3 DECAYS MOST OF THE SWELL TO LESS THAN 8 FT BY EARLY SUN.

$$ MUNDELL

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